His passions were gadgets and genealogy. ""He was the least reflective of men."" This is the official biography of Lord Louis Mountbatten (1900-1979) and it pronounces him, all told, ""a GREAT MAN."" But it is not a panegyric: not only are Mountbatten's well-known faults in evidence in Ziegler's scrupulous rendering, but also his unsuspected feet-of-clay. We see the personable, slogging naval cadet--already stung by his German-born father's forced exit (1914) as First Sea Lord--suddenly head his class, and determine never to settle for anything less. (His destroyer would have to win every competition--and it did.) He makes friends with clever, subversive sorts (left-wing M.P. Peter Murphy, Noel Coward); he compiles dossiers on the men under his command--groundwork for their fabled loyalty. He lives flamboyantly, works feverishly, strives mightily. He is married to heiress Edwina, his match in looks and panache but temperamentally his opposite--restless, peevish, independent, unfaithful. Quoting a touching, uncharacteristically humble letter--""l wish I could drive like Bobby Casa Maury, play the piano and talk culture like Peter. . . shoot like Daddy. . . play polo like Jack. I wish I knew how to flirt with other women, and especially with my wife""--Ziegler suggests that Mountbatten's rejection by Edwina ""was in part responsible for [his] furious ambition."" (A likelier cause, certainly, than wishing to avenge the wrong done his father.) Ziegler details Mountbatten's career to precisely define, and delimit, his accomplishments. Despite his heroization by Noel Coward in the film In Which We Serve: ""Mountbatten was not a good flotilla leader, nor wartime commander of destroyers."" (He was as impetuous at the helm of a ship as behind the wheel of a car.) But he was an energetic, imaginative organizer/administrator of Combined Operations--pioneer of amphibious warfare, proponent of Normandy as the invasion-site, champion of the artificial harbor, Mulberry. (If he sometimes claimed too much, he could often claim to have been a catalyst.) The Dieppe raid, one of the two black marks against Mountbatten, Ziegler finds flawed in concept, further compromised by decisions Mountbatten opposed, disastrously executed for reasons over which he had no control. (A sharp rebuke, here, to Montgomery biographer Nigel Hamilton.) As Supreme Commander, South-East Asia, he overcame formidable obstacles (not without missteps); as Viceroy of India, he could not have forestalled partition (""tragic but inevitable""), while delay would only have made matters worse--a view in which most authorities do concur. As for the relationship between Edwina and Nehru, Mountbatten is depicted as approving, even proprietary (one attitude Ziegler forebears to look into). Mountbatten's subsequent, lesser-known career gets no less close attention, as does his ""hyperactive"" retirement. Some will find Ziegler kindly--but he does achieve a firm, delicate balance.